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Respiratory System overview
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- Lakehead University (LakeheadU )
Respiratory system overview of the anatomy and workings of it
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NURS - 1080 WEEK 5 - Respiratory SystemFunctions of the Respiratory System
- 1. Pulmonary ventilation: air in/out of lungs
- 2. Pulmonary gas exchange: lungs - blood
- 3. Gas transport: via blood
- 4. Tissue gas exchange: blood - tissues
- A. Speech and sound
- B. Smell
- C. After abdominopelvic and thoracic pressures
- D. Acid- base balance of extracellular fluid
- E. Blood pressure and fluid regulation via contribution to synthesis of angiotensin-II
Module 21.3 Pulmonary Ventilation
Important Concepts for Ventilation (Air in and out)
- Pressure: Volume (Boyle’s Law)
- Inverse relationship when temp and gas molecules remain constant
- Inspiration/ Expiration are both dependent on volume changes of the thoracic cavity
- Thinking about pressure, what direction do gas molecules move?
- Atmospheric pressure: pull of gravity on surrounding air
- Inverse relationship with altitude
- Intrapulmonary pressure: air pressure within alveoli, equal with atmospheric pressure 2
in ventilation cycle
- Intrapleural pressure: pressure within the pleural cavity, always a negative gradient
compared to intrapulmonary
Mechanics of Inspiration and Expiration
- Volume changes of the thoracic cavity cause volume changes of lungs
- Muscles and thoracic cage - pleura - lungs
- Diaphragm
- External intercostals
- Internal intercostals
- Pectoralis minor
- Sternocleidomastoid
- Scalene
- Serratus anterior muscles
- Certain back muscles such as erector spinae muscle group
- Expiration - mostly passive (relaxation of inspiratory muscles)
- Also involves the recoil of elastic tissue
- Forceful expiration - uses accessory muscles:
, - Internal intercostals
- Abdominal muscles
- Quadratus lumborum muscles
- How might the heimlich maneuver resolve an airway obstruction?
Non-Respiratory movements
- Sigh
- Yawn
- Sneeze
- Cough
Factors that influence Pulmonary Ventilation
- 1. Airway resistance - airway diameter is main component
- 2. Alveolar surface tension - gas/water boundary, high surface tension can cause
alveolar collapse (atelectasis), surfactant opposes water surface tension to prevent
collapse
- 3. Pulmonary compliance
- Alveolar surface tension
- Stretch of elastic tissue
- Chest wall mobility
Infant Respiratory Distress Syndrome
- Surfactant is mainly produced in last 10-12 weeks of pregnancy
- Pre-term birth increases risk for surfactant shortage, also male gender, maternal
diabetes hx, cesarean delivery, family hx of RDS
- Widespread alveolar collapse due to surface tension and pulmonary compliance
Module 21.4 Gas Exchange
Gas Exchange
- Movement of oxygen and carbon dioxide
- Pulmonary gas exchange - alveoli/blood
- Tissue gas exchange - blood/cells
Principles relevant for Gas exchange
- Dalton’s law - total pressure of mixed gases is equal to sum of partial pressures of the
component gases
- Pressure gradient between blood/tissues/lungs drives movement of gas
- Henry’s law - degree to which gas dissolves in liquid is proportional to both partial
pressure and solubility in liquid (explains behaviour of gases in air that come in contact
with water in body)
- Nitrogen - high partial pressure in air (air is 78% nitrogen by volume); little
nitrogen in blood plasma because solubility in water is very low
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